Understanding Logarithmic Identities in Differential Equations

  • Context: Undergrad 
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Discussion Overview

The discussion revolves around the application of logarithmic identities in the context of solving differential equations. Participants explore the transformation of logarithmic expressions into exponential forms, particularly focusing on the identity that allows the coefficient of 1/8 in the logarithm to be represented as an exponent of 8 in the solution.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions how the expression 1/8 ln(y) is simplified to yield y = ce^(8t), specifically regarding the identity that allows the coefficient to become an exponent.
  • Another participant suggests multiplying both sides by 8 and then exponentiating, as a method to clarify the transformation.
  • A different viewpoint presents that 1/8 ln(y) can also be interpreted as ln(y^(1/8)), indicating an alternative perspective on the logarithmic identity.
  • Several participants engage in light-hearted banter about the challenges of remembering logarithmic identities, with humorous suggestions about tattooing them for easier recall during exams.

Areas of Agreement / Disagreement

Participants generally agree on the methods to manipulate logarithmic identities, but there is no consensus on the best approach to remember these identities or the implications of their application in exams.

Contextual Notes

The discussion includes informal exchanges and humor, which may distract from the technical aspects. Some participants express frustration over the perceived lack of clarity in instructional methods regarding logarithmic identities.

Who May Find This Useful

Students studying differential equations, individuals interested in logarithmic identities, and those seeking clarification on mathematical transformations in calculus.

HeLiXe
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This is related to differential equations, but I think my question has more to do with log identities than DE.

I keep seeing equations like

1/8 lny = t + c

simplified to get the solution

y = ce^8t

but I am unsure of the identity being used to get 1/8 into the exponent as 8. I already understand how everything else is simplified, just not this part. Thanks!
 
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Just multiply both sides by 8 and exponentiate both sides.

The other way to see this would be that [itex]1/8 ln(y) = ln(y^{{1}\over{8}})[/itex]
 
*facepalm* Thanks penguwino LOL
 
That'll be $5
 
I'll give you $25 :-p

I kept switching it over the entire semester and never understood why I was doing that loll. This is what happens when the "simple steps" are skipped in math -_-
 
Tattoo the logarithmic identities to your forearm. It's far more useful then some rose or star
 
^ But then to avoid being suspected of cheating, you'd have to wear full-sleeve shirts during your exams. And that sucks when your exams are seated outside during a heatwave :(
 
Pengwuino said:
Tattoo the logarithmic identities to your forearm. It's far more useful then some rose or star
I'll see if I can have them burned on my retina :D
Dr. Seafood said:
And that sucks when your exams are seated outside during a heatwave :(
That is so sadistic! -_- Who would ever do such a thing to an innocent student?
 
HeLiXe said:
I'll see if I can have them burned on my retina :D

Try to burn them behind your retinas.
That works even better! ;)


HeLiXe said:
That is so sadistic! -_- Who would ever do such a thing to an innocent student?

Oh, standard trick to flush out not-so-innocent students.
 
  • #10
I like Serena said:
Try to burn them behind your retinas.
That works even better! ;)

If there was something behind my retinae it would work better :-p
 

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